The present invention relates to a filter. In particular, embodiments of the present invention relate to improvements to a filter such as a fuel filter forming part of a fuel supply system for a vehicle. Certain embodiments of the present invention relate to a locking mechanism for a filter. In particular, certain embodiments relate to a locking ring forming part of a replaceable filter element. Alternative embodiments of the present invention relate to a filter element, which in conjunction with a filter head and a filter bowl provides for a predetermined fluid flow path through the filter.
Fuel supply systems, and in particular vehicle fuel systems generally comprise at least one fuel filter to remove water and other contaminants from the fuel. There may be multiple fuel filters in a fuel supply system, for instance a primary filter for filtering out water, air and large particulate contaminants on the suction side (that is, upstream of the main fuel pump) and a secondary filter for removing fine particles on the pressure side (that is, downstream of the main fuel pump).
Typically, a fuel filter includes a removable filter element including a filter media. This allows the filter media to be changed as it becomes clogged by contaminants without requiring the entire filter to be replaced. This prevents the pressure drop across the filter increasing beyond its designed range.
A fuel filter may typically comprise a filter bowl and a detachable filter head. The filter element may be seated within the filter bowl such that the fuel must pass through the filter media in order to reach an outlet located within the filter head. Fuel may pass into the filter bowl through an inlet located in the filter head at a position relative to the filter element such that the fuel passes around and then through the filter media. Alternatively, the inlet may be positioned in the side of the filter bowl.
It is known for the filter head to be coupled to the filter bowl such that they may be uncoupled in order to access and replace the filter element. The coupling may comprise a screw thread or a bayonet connection between the filter head and the filter bowl. However, for some known fuel filters, it can be possible for the filter head to be coupled to the filter bowl without a filter element being inserted into the filter bowl. This would allow unfiltered fuel to pass to the outlet in the filter head risking damage to the rest of the fuel system.
For fuel filters in which the fuel enters through an inlet positioned in the side of the filter bowl the fuel fills the bowl from the bottom upwards such that any air present floats above the fuel. A second outlet may be provided towards the top of the bowl or in the filter head to allow air to be returned to the fuel tank. However, for fuel filters in which the fuel inlet is in the filter head, fuel fills the bowl from the top making it harder for air to rise to the top of the filter and settle out of the fuel. This turbulent mixture of fuel and air can impede the flow of air from the filter through the second outlet. Excess air present in the fuel filter can reduce the filtering efficiency of the filter media.
It is an object of embodiments of the present invention to obviate or mitigate one or more of the problems associated with the prior art, whether identified herein or elsewhere. In particular, it is an object of certain embodiments of the present invention to provide a locking ring for a filter which reduces the possibility that the filter may be assembled without a filter media being present (the locking ring being couplable to the filter element or forming part of the filter element). Furthermore, it is a particular object of alternative embodiments of the present invention to provide a filter element which increases the filtering efficiency of the filter media for fuel filters which have a fuel inlet in the filter head.
In accordance with a first aspect of the present invention there is provided a filter element comprising: a locking ring; a first end cap coupled to the locking ring; a filter media coupled to the first end cap; and a locking rib extending outwardly from the locking ring; wherein the locking rib comprises a first portion which extends radially from the locking ring and a second portion which extends from the first portion around the periphery of the locking ring, at least part of the second portion of the locking rib being arranged to flex relative to the first portion of the locking rib, the locking rib forming part of a bayonet connection.
An advantage of the first aspect of the present invention is that if the locking rib is not present then a corresponding rib extending from a first filter body component cannot correctly engage a bayonet connector slot in a second filter body component. This reduces the risk that a filter can be assembled without a filter element being enclosed in the filter.